04 gp1300r crank seal blow out

Had booth rear crank seals blowout , 1st one out 2nd one half out , skl has 20hrs on rebuild hot rod crank, prox pistons, r&d headsv
! Ported cylinders, protec pipe, not sure if pipe is causing to much back psi on top end ???? Need help
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They was wsm seals , I believe they was in correct , in the groves, I think they have been out for a month, just noticed this weekend , ran fine on top end , but may have been running a little rich, I guess engine will need pulled again